Submitted to: Bemisia International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/3/2006
Publication Date: 12/3/2006
Citation: Naranjo, S.E., Ellsworth, P.C., Canas, L. 2006. Mortality and population dynamics of bemisia tabaci within a multi-crop system. P 50, In 4th International Bemisia International Workshop Proceedings, 3-6 December 2006, Duck Key, Florida.
Technical Abstract: Bemisia tabaci is a multivoltine insect with no diapause that maintains population continuity by moving from one host to another over the year. To better understand the mechanisms governing population development of this insect, whitefly “ecosystems” were established in three geographically and climatically distinct areas in Arizona. These systems consisted of a sequence of six representative hosts including winter broccoli, spring and fall cantaloupes, summer cotton, perennial alfalfa, various annual weeds, and the perennial ornamental, lantana. No insecticides were used at any site. Source and rates of natural mortality were quantified, in situ, on each host plant by constructing life tables. The same mortality factors were observed in all hosts at all sites. The quantitative contribution of each mortality factor varied among hosts and time of the year, but was relatively consistent among geographic sites. Predation and dislodgement from the plant surface were consistently the largest sources of mortality, although mortality from desiccation was high during the fall and winter. Most mortality occurred during the 4th nymphal stadium and the egg stage for most host plants. Median generational mortality was generally > 90% except on spring-planted cantaloupe where median mortality was ' 65%. Predation, dislodgement, desiccation, and occasionally parasitism, were the key factors depending on host plant, season and site. Low mortality during the spring on cantaloupe appears to act as a biotic release leading to outbreak populations during summer months. Overall, an understanding of the year round dynamics of this pest will greatly aid the development of better pest management strategies in all affected crops.